The production of nanostructures and of organized organic monolayers and multilayers as well as of semiconductor and metal quantum particles, has resulted in some achievements in recent years. The key issue for practical applications resides in good control of the dimensions, spatial location and stability of the assembled nanostructure. Recently, rather good control of the size of metals and semiconductor quantum particles as well as the number and stacking order of definite monolayers in a synthetic multilayer assembly have been achieved. However, genuine submicrometer architecture based on a planned assembly of nanoelements, can be achieved only by appropriate methods of precise positioning, spatial fixation and lateral interconnection of the desired nanostructures. The direct chemical synthesis of nanostructures on a patterned solid template capable of defining the position and lateral dimensions of growing objects might be the proper approach for nanofabrication, provided suitable versatile templates for growing the desired structures can be conveniently manufactured.
Surface nanopatterning of organic monolayers seems promising for preparing such templates with the desired chemical properties on the surface. Indeed, such patterning using conventional techniques of optical methods and lithographic schemes based on local degradation of the monolayer coating have been employed.
The possibility of achieving non-destructive surface patterning of a vinyl-terminated silane monolayer self-assembled on silicon, by the application of an electrical bias to a conducting atomic force microscope (AFM) tip operated in normal ambient conditions has been recently reported by the present inventors (Maoz et al., 1999). The tip-induced transformation was shown to proceed by local electrochemical oxidation of the top vinyl functions of the monolayer, with full preservation of its overall molecular order and structural integrity. It was further shown that such nanoelectrochemically patterned monolayers may be employed as extremely robust, stable templates for the controlled self-assembly of organic bilayer structures with predefined size, shape and surface location (Maoz et al., 1999).
However, post-patterning by chemical methods is subject to constraints posed by the need of site specificity. Only the tip inscribed sites should be affected, leaving the rest of the surface unmodified. Therefore, the use of base monolayer that are chemically sensitive restricts further chemical post-patterning.